A Trombe wall at the Rapid City (S.D.) Community Center South forms a large solar thermal collector.

A Trombe wall, developed by the French engineer Félix Trombe in 1956, is a sun-facing wall built from metal, stone, concrete or adobe that can act as a thermal mass. When combined with an air space behind it, insulated glazing and vents, it forms a large solar thermal collector. Heated air flows from inside the wall into interior spaces at night, when the average temperature of the thermal mass is significantly higher than room temperature.

The metal panels shown on the west and south faces of the Rapid City (S.D.) Community Center South are a proprietary system known as SolarWall™ that functions as Trombe envisioned. The air exchange serving the gymnasium (arched windows near the ceiling of the gym are visible) runs through the unit, bringing fresh, outside air through the space behind the panels to be passively heated during the long winter months, much like an air-to-air heat exchanger. Building architect Forefront Design Inc. of Rapid City notes that during the summer, the SolarWall can be bypassed or controlled with a dampering system.